It is desired to use microelectronic circuit constructions in many applications to provide miniature electronic equipment. One such application is in miniature radio devices which are of a size to be held in the hand or worn on the person. One problem with such circuits is that miniature components which are available are not adjustable, and it is difficult to work with the same to tune or align the circuit because of the small size. In many cases the circuit must be constructed and then tested, and if the circuit operation is not within the desired limits, it is necessary to replace components, which is very time consuming and adds substantially to the cost of the circuit.
In the construction of microelectronic circuits, hybrid constructions have been used wherein certain components are formed by conductors on an insulator or substrate and other components are soldered or otherwise secured to the conductors. Inductors have been provided by spiral and microstrip conductors provided as coatings on the insulator. It has been proposed to vary the inductance value of the coils by bridging conductors across portions of the coils, but this requires a soldering operation which heats the substrate and may unsolder components which have been connected to the conductors. Although separate adjustable inductor elements can be used, these are relatively large and must be individually connected to the circuit. Accordingly, the use of a separate adjustable element results in a substantial increase in size and cost.